1. Field of the Invention
The present invention relates to a focus controller for an image pickup apparatus.
2. Description of the Related Art
A contrast method has been known as one of auto focus (hereinafter, referred to as AF) control methods. In the contrast method, a focus lens is moved in the optical axis direction to evaluate the contrast of the subject. The lens position of the maximum contrast of the subject is set as a focus position. The focus lens is moved to the focus position. In a usual contrast method, a signal is obtained by scanning a pixel part provided in an imaging unit. An evaluation value (AF evaluation value) is calculated according to the signal. The evaluation value is evaluated to evaluate the contrast of the subject.
Techniques relating to such a contrast method are proposed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 2007-57763 and Jpn. Pat. Appln. KOKAI Publication No. 2009-21929.
Jpn. Pat. Appln. KOKAI Publication No. 2007-57763 proposes that, to control the movement of the focus lens, both evaluation values are used: one is calculated from the signal obtained by scanning the pixel part provided in the imaging unit in the vertical direction; and the other is calculated from the signal obtained by scanning the pixel part in the horizontal direction. Further, Jpn. Pat. Appln. KOKAI Publication No. 2007-57763 proposes that, to control the movement of the focus lens, the larger evaluation value or, namely, the evaluation value having more high frequency components is weighted.
Jpn. Pat. Appln. KOKAI Publication No. 2009-21929 proposes that motion vectors in the image are calculated from the signals obtained by scanning the pixel part, the evaluation values are weighted based on the motion vectors and added, and the added evaluation values are used to control the movement of the focus lens in an image pickup apparatus where both evaluation values are used: one is calculated from the signal obtained by scanning the pixel part in the vertical direction; and the other is calculated from the signal obtained by scanning the pixel part in the horizontal direction in order to control the movement of the focus lens.